I’ve always felt like the TOS movies were better than the TOS show, but the TNG show was better than the TNG movies.
My reasoning is: the TOS campiness was great, but the 2-3-4 trilogy especially highlighted the strengths of the cast, and the slightly more militaristic Starfleet actually worked (and don’t even get me started on them red uniforms… Mm). STVI is likely the best political story in the entirety of the TOS canon.
Meanwhile, TNG the show was tackling themes that TOS would have never touched. I suspect it actually may have a lot to do with the fact that the last few TOS movies and the TNG show were made at roughly the same time.